Effect of sintering temperature and sintering additives on the properties of alumina ceramics fabricated by binder jetting

Binder jetting (BJ), a promising additive manufacturing technology for fabricating ceramic components, is currently limited by drawbacks such as high sintering temperature, low density, and poor mechanical performance. In this study, Ca(OH)2–MgO–SiO2 was introduced as a sintering additive for improving the properties of Al2O3 ceramics during the BJ process. The effect of the sintering additive content and sintering temperature on the relative density, microstructure, and mechanical properties of the fabricated Al2O3 ceramics was analyzed by scanning electron microscopy, X-ray diffraction, and universal testing. The results show that during the sintering process, sintering additives react with Al2O3 to form a liquid ceramic phase, which contributes to the reduced porosity of the green body and the increased relative density and mechanical strength of the final ceramic parts. The shrinkage along the Z-axis reaches to 37%, the relative density achieves its highest value of 83.3%, and the compressive strength also reaches to the maximum of 58.7 MPa when 30% content of sintering additives and sintering temperature of 1500 °C are used, which is better than that in previous studies. It suggests that adding sintering additives provides a feasible method to fabricate Al2O3 ceramics with agreeable performance via the BJ process.